Determination of Hexavalent Chromium (Cr(VI)) Concentrations via Ion Chromatography and UV-Vis Spectrophotometry in Samples Collected from Nacogdoches Wastewater Treatment Plant, East Texas (USA)

Table 1

UV-Vis absorbance and concentrations of wastewater samples spiked with different volumes of a 0.5 ppm Cr⁺⁶ standard at 540 nm using standard addition method; .

NWWTP; treatment stages	Concentration (ppm) of Cr(VI) spiked	Absorbance (mean ± SD)	Determined Cr(VI) concentration (ppm)	% RSD
Aeration chamber	0.1	0.024 ± 0.002	0.009 ± 0.006	67
	0.2	0.045 ± 0.001
	0.3	0.068 ± 0.001
Clarifier	0.1	0.023 ± 0.001	0.007 ± 0.005	71
	0.2	0.045 ± 0.001
	0.3	0.066 ± 0.001
Chlorination chamber	0.1	0.024 ± 0.001	0.008 ± 0.006	75
	0.2	0.045 ± 0.001
	0.3	0.068 ± 0.002
Sulfur dioxide chamber	0.1	0.022 ± 0.001	0.004 ± 0.006	150
	0.2	0.043 ± 0.001
	0.3	0.067 ± 0.001